The invention relates to a drive device for motor vehicle sliding sunroofs, having two flexible drive transmission elements which are in driving connection, one on one side and the other on an opposite side of a displaceable element that is displaceable in one direction or another direction of movement, in the form of a cover of the sliding sunroof construction, with guide components for the displaceable element, and which may be synchronously displaced in the one or the other direction of movement by engagement with a rotatable toothed pinion, which may be selectively driven in one or another direction of rotation.
The term xe2x80x9cmotor vehicle sliding sunroofxe2x80x9d or xe2x80x9csliding sunroofxe2x80x9d, used alone or in phrases, is intended, for the purposes of the present invention, to cover all designs in which at least one cover is associated displaceably with a roof opening of a motor vehicle and is movable by means of the drive device. These include designs in which the cover may be slid under the fixed rear roof surface to uncover the roof opening after lowering of its rear edge and also slide and lift sunroofs, in which the cover may additionally be tilted from its position closing the roof opening about a tilt axis provided in the vicinity of its front edge so as to project above the fixed roof surface. Finally, this definition is also intended to cover those designs in which the cover may be displaced more or less to the rear over the fixed rear roof surface after lifting of its rear edge (xe2x80x9cspoiler roofsxe2x80x9d). Roof designs are also included in which at least one cover is made not of sheet metal or glass but as a folding roof of flexible surface material.
Common to all the known drive devices of the above-mentioned type (e.g. DE 38 03 816 A1, DE 38 09 949 A1, DE 195 31 514 C1, DE 32 21 487 A1) is that the two flexible drive transmission elements are drive cables consisting of a stranded flexible core of steel wires, onto which a xe2x80x9cworking windingxe2x80x9d of a steel wire of circular cross section is firmly wound in the manner of a helix. The pinion located stationarily on the sliding sunroof construction and driven via a crank handle transmission or an electric gear motor engages with its toothing directly in the working windings of both drive cables in the manner of a rack drive. The drive cables are guided displaceably in tensile stress- and compression-resistant manner in guide channels and/or guide tubes and transmit the adjusting and actuating movements to the guide components of the cover, with which they are in driving connection.
These drive devices with drive cables as drive transmission elements, which have been known for a long time and used on a large scale, have been constantly further developed and have definite advantages but also design-dependent disadvantages. For instance, an ideal tooth shape on the pinion, which would correspond to a normal optimised toothed gear, cannot be achieved because of the circular cross-sectional circumference of the wire working winding and the unavoidable dimensional tolerances with regard to the drive cable, the pinion itself and the guide elements for the drive cables. Moreover, it cannot be ensured that there is always at least one tooth of the pinion engaged with each of the two drive cables, resulting in jerky, uneven advance of the drive cables. At the same time, the active circle of the pinion changes due to play in the tooth engagement movement, and also due to resilient deflection movements of the drive cables. As a consequence, when the known drive devices are actuated, vibrations may be excited which are transmittable to the frame structure of the sliding sunroof and thus to the vehicle roof itself, whereby disturbing noise may develop during adjusting and driving movements of the sliding sunroof, especially when the pinion is driven by an electric motor. Due to the inevitable contact between the working winding and the walls of the guide elements for the drive cables, disturbing scraping noises and increased material abrasion at the corner radii of the cable guides may arise during adjusting and driving movements. Finally, it should also be mentioned that the manufacturing method for the drive cables is relatively complex, such that the drive cables have a considerable effect on the cost of the known drive devices.
The object of the invention is to provide a drive device of the above-mentioned type, which allows even, low-noise adjusting and driving movements of the drive transmission elements to be achieved without vibration excitation while keeping the design of the drive device simple and economic.
According to the present invention, there is provided a drive device for motor vehicle sliding sunroofs, having two flexible drive transmission elements which are in driving connection, one on one side and the other on an opposite side of a displaceable element that is displaceable in one direction or another direction of movement, in the form of a cover of the sliding sunroof construction, with guide components for the displaceable element, and which may be synchronously displaced in the one or the other direction of movement by engagement with a rotatable toothed pinion, which may be selectively driven in one or another direction of rotation; wherein the two flexible drive transmission elements take the form of endless, tensile stress-resistant toothed belts, which are provided on an inside thereof with internal toothing complementary to the toothing of the pinion, wherein deflection of the two toothed belts takes place at one end in each case with partial wrap of the pinion and at the other end in each case by means of a deflection element.
The use according to the invention of endless toothed belts as drive transmission elements allows the avoidance of all the cited disadvantages of drive cables. The endless toothed belts transmit only tensile forces to the guiding and adjusting components located on each side of the cover. The toothed belts have a continuous force profile, such that driving engagement may be achieved at any point apart from the deflection points of the toothed belts, wherein driving engagement for the guiding and adjusting components each side of the cover is intended to be effected at toothed belt portions moving in the same direction. Due to the partial angle of wrap of the toothed belt, which amounts preferably to 180xc2x0 of the pinion circumference, a plurality of pinion teeth are always engaged with toothed belt teeth, such that no noise-generating influences may result from the tooth engagement situation.
Where xe2x80x9cendlessxe2x80x9d toothed belts are mentioned herein, the term naturally includes those toothed belts which are produced to start with as toothed belt pieces of the desired total length or are cut to length, their two ends optionally being joined together in a suitable manner to form an endless toothed belt after installation on the drive device.
The internal toothing of the toothed belts and the pinion is advantageously spur toothing, so optimising tooth engagement. If the tooth flanks on both sides are constructed appropriately, virtually play-free tooth engagement may be achieved.
To reduce friction in the drive system, the deflection elements are advantageously constructed as deflection rollers mounted rotatably on the sliding sunroof construction, which deflection rollers may, in the event of corresponding guidance of the toothed belts, correspond in thickness approximately to the toothed belt width, i.e. they may be simply disk-shaped in the interests of keeping the structural height of the drive device low. Like the driven pinion, the deflection rollers are preferably provided with toothing in which the internal toothing of the toothed belt engages.
In a further development of the drive device, the tension of the toothed belts may be adjusted in each case by means of a tensioning device. These tensioning devices are preferably in active connection with the deflection rollers. It is expedient for the deflection rollers to be mounted rotatably on fixable tensioning slides. The tensioning slides may however also be permanently spring-loaded for tensioning of the toothed belts.
The guide components on each of the two cover sides are in driving connection in each case with one of the toothed belts for driving the cover, so that the cover may be simultaneously and synchronously driven on both sides. The driving connection between the toothed belts and the guide components may be achieved in each case by the engagement between the internal toothing and a correspondingly profiled driving member fixed to the guide component.
The toothed belts may exhibit the cross-sectional shape of a flat rectangle, having longer edges which form the inside or the outside of the toothed belts. A toothed belt width of approximately 4 mm, corresponding approximately to the height or thickness of the pinion in some of the embodiments, is sufficient for the purposes of the present invention, thereby contributing to an advantageously small structural height of the drive device. To construct toothed belts which exhibit good flexibility and which exhibit sufficient tensile strength to transmit forces of approximately 400 N per cover side, a plurality of embodiments are available. For example, the toothed belts may be made from a toothed plastics band or a link chain.
A readily bendable, tensile stress-resistant insert may be molded continuously into the plastics band. The tensile stress-resistant insert may be a metal band or rope resistant to fatigue under reversed bending stresses. The insert may be embedded by injection-molding in the plastics, which also forms the internal toothing.
In a further development of the present concept, all the functional components of the drive device, such as toothed belts, pinions, deflection elements and tensioning device, are attached to a guide frame of the sliding sunroof construction, such that, even before installation on the motor vehicle, a functional, ready-to-install module is available, wherein the electromotive drive may optionally also already be attached to the guide frame.
The toothed belts may advantageously be guided in guide channels which are provided on the guide frame. In the configuration of the guide channels, attention must be paid to the need for the driving members to be able to engage with the toothed belts in the cover movement area and to the toothed belt installation requirements.
In the interests of achieving an optimum coefficient of friction for the toothed belts relative to the wall surfaces of the guide channels, the wall surfaces may be formed in a particular way as a function of the material of the toothed belts and/or the surface condition thereof, be it through an appropriate material pairing and/or an appropriate surface coating for the wall surfaces.
The invention permits both joint drive of both toothed belts by means of one driven pinion and the association of a driven pinion with each toothed belt, wherein, in the latter case, the following embodiment alternatives are preferred for the synchronous running required. Namely, a common electric gear may be provided for both toothed belts, which motor is connected via two drive shafts with the two rotatable toothed pinions in each case via an angular gear arrangement. Alternatively, an electric motor may be provided for each of the two rotatable toothed pinions and is connected via an angular gear arrangement with the relevant pinion, wherein the two electric motors are run in synchronised manner.